The present invention relates to a stationary fire grate having circular or square planform thereof, which is placed in the low region of the incineration chamber of an incinerator furnace.
Up to the present time, the circular stationary fire grate used in refuse-burning incinerator furnaces has been of basically plain circular-late type grate with circular holes or fan-shaped planform openings therein to provide discharge passage to ash sifting of the waste materials being burned on the fire grate and/or air passage therethrough from underneath to supply combustion supporting air to the waste material dumps on the fire grate. Even with intimate-contact preventing means on the single-body circular fire grate such as U.S. Pat. No. 4,924,847, there is no central and/or radially laid out and circumferentially and integrally disposed means for supporting the fire grate to prevent deterioration of structural stiffness of the fire grate exposed to extreme heat of the furnace operating temperature so that application of those embodiments on the incinerator furnace with circular incineration chamber having inside diameter of up to three or four meters to have big incineration capacity is impossible.
Due to high cost of manufacture of rigorous agitation mechanism in the conventional circular planform fire grates for provision of wide enough refuse-air contact areas to meet stoichiometric condition in the incineration chamber and also due to poor reliability of the rotary grate owing to complicated and thus costly structures thereof, there has been a need for square planform fire grates having a unidirectional agitational means therein.
On the other hand, there has been a need for provision of agitational effect to stationary fire grates irrespective of planform shape of the fire grates. U.S. Pat. No. 27,876 shows an embodiment of corrugated fire grate upper surface profile in one direction of the fire grate. This embodiment is, however, not provided with said intimate-contact preventing means thereon and with air admission holes through which combustion supporting air is admitted from underneath the fire grate so that application of this fire grate is limited to small size incineration furnace if applied in the incineration chamber of an incineration furnace.
Due to the above mentioned negative features and limitations of the conventional stationary fire grates, scaling up in diameter of the incineration chamber of the incinerator furnaces wherein the fire grate is implemented to take care of massive incineration of municipal and industrial refuses has been restricted to small size incineration furnace, which is mainly due to the deterioration of the structural rigidity at high furnace operating temperature. Under these circumstances, the advent of stationary fire grate provided with intrinsic intimate-contact preventing means for providing larger air space between the refuse fuel being incinerated thereon and the upper surface of the fire grate has been anticipated to achieve less number of parts used for a large capacity incinerator furnace while maintaining agitational effect and structural rigidity at elevated temperature ranges irrespective of the planform shape of the fire grate, resulting in low cost both in manufacture and in maintenance thereof and in enhanced reliability.